Even When You Know
Changing which job you are doing costs you time. Being told in advance buys some of that back. This page measures how much, and then measures the part that stays no matter how long you are given.
The last three pages in this lab measured what one decision costs: your hand as a channel, choosing as a channel, and the queue that runs exactly one decision at a time. This one asks the question sitting underneath all of them. What does it cost to change which decision you are making?
A letter and a digit will appear together in one corner of a square. Top half, judge the letter: vowel or consonant. Bottom half, judge the digit: even or odd. The pair moves one corner at a time, always the same way round the square, so the tasks go letter, letter, digit, digit, letter, letter, forever.
and you can see every one of them coming
That last part is the whole design. You are never told what to do. You always already know. Rogers and Monsell built it this way in 1995 for exactly one reason: if a page has to flash LETTER or DIGIT at you, then a large part of what it measures is you reading the word.
Only one thing changes between blocks: the gap between your answer and the next pair. 150 ms, 400 ms, 900 ms, 1600 ms. It is dead time. You already know what is coming. All the gap does is give you room to get ready.
Give people more room and the switch cost falls. Ordinary. What is not ordinary is where it stops falling. It drops fast, it flattens, and then a stubborn lump of it sits there and another full second of warning buys nothing at all.
both halves measured on your hands, in the same run
Yesterday's page had a headline number that was supposed to be zero. This one has a headline number that will not become zero however much notice you are given.
consonant right
odd right
Keyboard: F is left, J is right. On a phone the two buttons at the bottom do the same job. Answer fast and answer right; a run with more than a quarter of its answers wrong is refused rather than scored. About nine minutes, fifteen practice trials first, escape aborts at any time.
Everything runs in your browser. Nothing is recorded. Nothing leaves the page.